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This lichen is fully hydrated (3 inches of rain last night), and yet remains gray, and has not turned green as it would if it were Physcia americana.

EDIT - I forgot to note: on rock/saxicolous/epipetric.

This lichen is so infrequently observed, I decided to post another observation from the same rusting steel pole as my other two observations of the same day. I found this nice rosette in accompaniment of a Xanthoparmlia cumberlandia I had photographed, here intruding at the upper left in this photo cropped from the original.

EDIT: Link to my 2 other observations - https://www.inaturalist.org/observations/197414055

Found on a common coyway growing in a rainforest on the delta of the baker river, near tortel. Growing at 5m above sea level, and between 1-4 meters on trees. The “leaves” of the lichen were up to 4 cm wide and had a pale light mint green color on top and a creamy white color underneath with large orange brown spots. The “leaves” were also very curled and textured, giving them volume away from the trunk of the tree although some of them above the rest of the leaves were flush against the tree. I wonder if the orange/brown patches on the underside are to release spores, and if not what their function is

The observation is for the protrusions on the upper surface of this Dermatocarpon (for which a separate observation has been made: https://www.inaturalist.org/observations/192663915).

I conjecture that they are the result of a lichenicolous fungus, but that speculation is not affirmed by the Flora of Lichenicolous Fungi, 2022, the contents of which do not include the genus Dermatocarpon.

EDIT, 30 November 2023, 6:46pm Eastern Standard Time: Flora of Lichenicolous Fungi, 2022, pages 265-6, does have Tremella umbilicariae, known to parasitize species of Umbilicaria, of which Dermatocarpon is a related genus.

Matches the description of Physconia subaquila.

• upper desiccated surface gray-green
• hydrated upper surface deep green
• perimeter of lobes with frosted upper surface
• lower surface black
• on rock/saxicolous/epipetric
• east-facing vertical rock
• in a humid environment above the waters of the river
• apothecia absent (any Anaptychia palmulata of this size would be adorned with dozens of apothecia)